//
// Copyright 2019 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import Foundation

final class SourcesComparator: Comparator {
    private typealias SourcePair = (first: SourceDescriptor, second: SourceDescriptor)

    let tag = "sources"
    private let targetsHelper = TargetsHelper()

    func compare(
        _ first: ProjectDescriptor,
        _ second: ProjectDescriptor,
        parameters: ComparatorParameters
    ) throws -> [CompareResult] {
        let commonTargets = try targetsHelper.commonTargets(first, second, parameters: parameters)
        return try commonTargets
            .map { firstTarget, secondTarget -> CompareResult in
                let firstSources = try targetsHelper.sources(from: firstTarget, sourceRoot: first.sourceRoot)
                let secondSources = try targetsHelper.sources(from: secondTarget, sourceRoot: second.sourceRoot)

                return result(
                    context: ["\"\(firstTarget.name)\" target"],
                    first: firstSources,
                    second: secondSources,
                    diffCommonValues: { commonPairs in
                        compilerFlagDifferences(in: commonPairs)
                    }
                )
            }
    }

    /// Returns compiler flag differences between source pairs
    private func compilerFlagDifferences(
        in sourcePairs: [SourcePair]
    ) -> [CompareResult.DifferentValues] {
        return sourcePairs.compactMap { sourcePair in
            let (first, second) = sourcePair
            if first.flags != second.flags {
                return CompareResult.DifferentValues(
                    context: "\(first.path) compiler flags",
                    first: first.flags,
                    second: second.flags
                )
            }
            return nil
        }
    }
}
